Liquid ring vacuum pumps typically have a housing with two port-containing cone members positioned inside each end of a rotor, although the pump can have just a single cone and rotor. Port-containing cone members have a large base end, a small end opposite the base end, and a cone wall extending between the large base end and the small end. Typically, the cone wall is tapered between the large base end and the small end thereby giving the port-containing cone member a frustoconical shape.
The rotor, which is coaxially mounted with the cone axis, rotates around the two port-containing cone members. Rotation of the rotor causes seal water located in the housing to form a cylindrical liquid ring that is shaped by the rotation of the rotor within the off-centered housing. In operation, movement of an off-centered cylindrical liquid ring around the port-containing cone member creates a disparity of volumes, and therefore varying pressures, around the port-containing cone member. The liquid ring acts like working pistons to reduce the volume and thereby increase the pressure of a gaseous medium within the liquid ring vacuum pump. The resulting disparate pressures force the gaseous medium to be positively displaced from an inlet port of the liquid ring vacuum pump, compressed by the cylindrical liquid ring or liquid ring pistons and then forced out through a discharge port in the liquid ring vacuum pump.
The port-containing cone member can be described as having an intake or inlet segment, a compression segment, a discharge segment, and a cone seal segment located between the discharge segment and the inlet segment. The port-containing cone member has an intake or inlet port located in the inlet segment and a discharge port located in the discharge segment. The cone seal segment is the area of the cone wall located between a closing edge or trailing edge of the discharge port and opening edge or a leading edge of the inlet port.
Seal water serves four purposes. First, as previously described, seal water forms the cylindrical liquid ring which performs like working pistons that compress the gaseous medium in the liquid ring vacuum pump and forces the compressed gas out of the pump. Second, seal water acts as a heat transfer vehicle to remove the heat of compression that is generated by the compressing action of the liquid ring vacuum pump. Third, seal water forms a seal between the high-pressure gas being discharged from the pump and the low-pressure gas entering the pump. The seal is formed in an approximate 30 degree segment of the cylindrical liquid ring where the liquid ring pistons contact the outer cone wall surface of the port-containing cone member. Preferably, the cylindrical liquid ring pistons exactly intersect and fully contact the cone wall surface without wasteful hindrance of an air flow through the inlet port or excessive discharge of seal water at the discharge port. Finally, seal water lubricates the packing rings around the shaft of the rotor housing.
The operating capacity of the liquid ring vacuum pump, as well as its efficiency, depends upon the integrity of the seal created between the cylindrical piston ring or cylindrical liquid ring and the port-containing cone member at the cone seal segment. An improper intersection of the cylindrical piston ring with the outer cone wall surface can restrict the amount of low pressure gas which can freely enter the inlet port, thereby reducing pump capacity. Also, an improper intersection of the cylindrical piston ring with the outer cone wall surface can restrict the amount of high pressure gas which can freely exit the discharge port, thereby reducing pump capacity and increase power required or worsen efficiency. Therefore, to maximize pump capacity, while minimizing operating cost, it is desirable to have a cone seal segment that fully supports the cylindrical liquid ring or piston ring.
The cone seal segment on the cone wall of an existing port-containing cone member typically has a delta wing port configuration. Because the edges of the ports of "delta wing cone members" do not align with the parabolic shape defined by the intersection of the cylindrical liquid ring with the cone wall surface, a delta wing cone member does not fully support the cylindrical liquid ring. Consequently, delta wing cone members allow cylindrical piston ring liquid to flow into the inlet port and thereby restrict the free flow of air or gas into the inlet port. Additionally, delta wing cone members allow unsupported amounts of the cylindrical piston ring liquid to flow into the discharge port of the port-containing cone member, thereby restricting the flow of compressed gas out of the pump, wastefully discharge seal water out of the pump, and require extra power.
The inflow of fugitive cylindrical ring liquid into the ports of the delta wing cone member decreases the available volume inside the cone member. The reduction of the available volume in the port-containing cone member diminishes the capacity of the liquid ring vacuum pump.
Furthermore, because the cylindrical liquid ring must be maintained at an optimal level in the rotor in order for the pump to operate properly, unnecessary losses of the cylindrical liquid ring, beyond that needed to remove the heat of compression, must be replaced. This requirement for replacing unnecessarily lost seal water increases the operating cost of the liquid ring vacuum pumps.
A need, therefore, exists for a port-containing cone member having inlet and discharge port edges which provides a cone seal segment that fully supports liquid ring pistons located over the cone seal segment and thereby prevents the excessive flow of liquid into the discharge port and the movement of liquid into the inlet port and optimizes the volume of gas entering the inlet port.